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Obs: Make sure to change the default password for Raspbian.

Measurements

We chose to make detailed measurements from two MAs at SLAC.

Requirement

Two major points need to be addressed before we can comfortably deploy Raspberry PI MAs.

1. The Raspberry Pi PingER MA must be robust and reliable. It needs to run for months to years with no need for intervention. This still needs to be verified, so far the Raspberry Pi has successfully run without intervention for over a month. This has included automatic recovery after two test power outages. 
2. The important metrics derived from the measurements made by the Raspberry Pi should not be significantly different from those made by a bare metal PingER MA, or if they are then this needs to be understood.

We define the important metrics measured by PingER as being the minimum, average, median and jitter of the RTTs, the packet loss, together with the reachability (i.e. a target host is unreachable when no ping requests are responded by the target host). These are the main metrics that impact applications such as throughput, voice over IP, streaming video, haptics, and estimating the geolocation of a host by pinging it from well know landmarks.  Such differences might result in significant discontinuities in the metric measurements if we were to change the monitoring host from a bare metal server to a Raspberry Pi.

In this report the jitter is represented by the Inter Packet Delay (IPD), the absolute values of the IPF (Abs(IPD)) and the Stdev(IPD).

Measurements

We chose to make detailed measurements to and from two MAs at SLAC.

1. The Dell Poweredge 2650 bare metal pinger.slac.stanford.edu server running Red Hat Linux  2.6.32-504.8.1.el6.i686

   Code Block
   pi@pinger-raspberry ~ $ uname -a Linux pinger-raspberry.slac.stanford.edu

   The Dell Poweredge 2650 bare metal pinger.slac.stanford.edu server running Red Hat Linux  2.6.32-504.8.1.el6.i686

   Code Block
   pi@pinger-raspberry ~ $ uname -a Linux pinger-raspberry.slac.stanford.edu 3.18.11+ #781 PREEMPT Tue Apr 21 18:02:18 BST 2015 armv6l GNU/Linux

2. The Raspberry Pi pinger-raspberry.slac.stanford.edu an armv61 running Gnu Linux (see above).

   Code Block
   103cottrell@pinger:~$uname -a Linux pinger 2.6.32-504.8.1.el6.i686 #1 SMP Fri Dec 19 12:14:17 EST 2014 i686 i686 i386 GNU/Linux

Both were in the same building at SLAC, i.e. roughly at latitude 37.4190 N, longitude 122.2085 W, but on different floors. The machines are about 30 metres apart or about 0.0003 msec based on the speed of light in a direct fibre. 

The measurements were made:

• between pinger.slac.stanford.edu and pinger-raspberry.slac.stanford.edu
• from both pinger.slac.stanford.edu and  pinger-raspberry.slac.stanford.edu to targets at varying distances and hence varying minimum RTTs from SLAC.
• from two representative MAs at sitka.triumf.ca and ping.cern.ch to pinger.slac.stanford.edu and pinger-raspberry.edu

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49.2475 N 

123.2308 W

46.23 N

6.07 E

Requirement

Two major points need to be addressed before we can comfortably deploy Raspberry PI MAs.

1. The Raspberry Pi PingER MA must be robust and reliable. It needs to run for months to years with no need for intervention. This still needs to be verified, so far the Raspberry Pi has successfully run without intervention for over a month. This has included automatic recovery after two test power outages. 
2. The important metrics derived from the measurements made by the Raspberry Pi should not be significantly different from those made by a bare metal PingER MA, or if they are then this needs to be understood.

We define the important metrics measured by PingER as being the minimum, average, median and jitter of the RTTs, the packet loss, together with the reachability (i.e. a target host is unreachable when no ping requests are responded by the target host). These are the main metrics that impact applications such as throughput, voice over IP, streaming video, haptics, and estimating the geolocation of a host by pinging it from well know landmarks.  Such differences might result in significant discontinuities in the metric measurements if we were to change the monitoring host from a bare metal server to a Raspberry Pi.

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49.2475 N 

123.2308 W

46.23 N

6.07 E

The following plots are the raw metric data from the MA measurements from which we have to craft our text (with some plot examples).

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Example target = pinger.unimas.my (~220 msec.)

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